Static Route
Course Contents
1. Introduction to Static Routing
Static route is a manual method of routing where network administrators explicitly define routes in a router’s routing table. Unlike dynamic routing protocols which automatically adjust to network changes !
Let’s consider a practical example to understand the need for static routing.
In this network:
- R1 is connected to Network 192.168.1.0/24 on interface G0/1.
- R2 connects Network 192.168.1.0/24 on interface G0/0 and to Network 192.168.2.0/24 on interface G0/1.
The Problem:
R1 cannot communicate with the 192.168.2.0/24 network because there is no route in its routing table pointing to that destination.
R1# show ip route C 192.168.1.0/24 is directly connected, GigabitEthernet0/1
Without an entry for 192.168.2.0/24, R1 does not know where to send packets.
Testing Connectivity:
R1# ping 192.168.2.1
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
The ping fails because R1 lacks a route to the 192.168.2.0/24 network.
2. Understanding Static Routes
Static routes are manually defined paths in a router’s routing table.
This type of route need a specific IP address (next-hop IP) that the router will use to reach the given network.
Components of a Static Route:
- Destination Network: The target network
- Subnet Mask: The mask of the destination network
- Next-Hop IP: The IP address of the next router that indicates the path to the destination network
- Administrative Distance (AD): An optional parameter to define the priority of the route. If omitted, a default AD of 1 is applied.
Administrative Distance (AD)
Static routes have an Administrative Distance (AD) of 1 by default, making them more trustworthy than most dynamic routing protocols (example RIP: 120, OSPF: 110). This ensures the static route is preferred over other routes !
3. Configuring Static Routes
Now that we understand the problem and the theory, let’s solve it by configuring a static route.
Configuration Command
R1(config)# ip route 192.168.2.0 255.255.255.0 192.168.1.2
Now we can see in the routing table our route to 192.168.2.0/24 using 192.168.1.2 as the next-hop:
R1# show ip route
S 192.168.2.0/24 [1/0] via 192.168.1.2
C 192.168.1.0/24 is directly connected, GigabitEthernet0/1
R1 now has a static route pointing to the 192.168.2.0/24 network via the next-hop 192.168.1.2 with AD set to 1 (by default).
Testing Connectivity After Configuration
R1# ping 192.168.2.1
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/3 ms
The ping is now successful because the static route allows R1 to forward packets to the 192.168.2.0/24 network via R2.
4. Verifying and Troubleshooting Static Routes
To confirm that static routes are correctly configured and active, use:
R1# show ip route S 192.168.2.0/24 [1/0] via 192.168.1.2 C 192.168.1.0/24 is directly connected, GigabitEthernet0/1
The static route is present and marked with an “S” indicating that it is manually configured.
Troubleshooting Static Route Issues
Common Issues and Solutions:
- Missing Route Entries: Ensure the syntax and next-hop address are correct.
R1# show running-config | section ip route ip route 192.168.2.0 255.255.255.0 192.168.1.2
2. Incorrect Next-Hop Address: Verify connectivity to the next-hop router using ping.
R1# ping 192.168.1.2 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/3 ms
3. Interface Down: Check interface status.
R1# show ip interface brief Interface IP-Address OK? Method Status Protocol GigabitEthernet0/1 192.168.1.1 YES manual up up GigabitEthernet0/0 unassigned YES unset administratively down down
5. Conclusion
Static routing is a method where routes are manually defined on a router instead of being dynamically learned ! 🙂